uitabbarcontroller - iPhone ModalViewController 来自第一个标签栏视图

Question

我正在尝试在加载 TabBarController 视图之前启动初始登录/注册屏幕。我已经读过将 ModalViewController 放在第一个视图中是一个不错的方法。这可行，但我正在尝试将导航控件添加到 ModalViewController。我遇到以下问题：

1 - 错误：在“AppDelegate”类型的对象上找不到属性“navigationController”

2 - 警告：使用不兼容类型“id”的表达式初始化“AppDelegate *”

这是我的 ModalViewController 上的代码：

-(IBAction)signUpButtonTapped {
// i need to get the control for main navigation controller
AppDelegate *appDelegate = [[UIApplication sharedApplication]delegate];
[appDelegate.navigationController popToRootViewControllerAnimated:NO];
// create object from app main view to push it
SignUpViewController *signUpViewController = [[SignUpViewController alloc] initWithNibName:@"SignUpViewController" bundle:nil];
[AppDelegate.navigationController pushViewController:signUpViewController animated:YES]; }

有人有想法么？非常感谢！

Answer 1

您的代码中有两个问题

1) 使用类名访问 OBJECT。它必须是appDelegate.nav...（a对于解决 1 错误来说很小）

[appDelegate.navigationController pushViewController:signUpViewController animated:YES];

2）类型转换分配（用于解决2警告）

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];

因此，您的完整工作代码必须为

-(IBAction)signUpButtonTapped {
  // i need to get the control for main navigation controller
  AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];
  [appDelegate.navigationController popToRootViewControllerAnimated:NO];
  // create object from app main view to push it
  SignUpViewController *signUpViewController = [[SignUpViewController alloc] initWithNibName:@"SignUpViewController" bundle:nil];
  [appDelegate.navigationController pushViewController:signUpViewController animated:YES]; 
}

Answer 2

在您的代码中修改此行

AppDelegate *appDelegate = [[UIApplication sharedApplication]delegate];

作为

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

现在试试

Answer 3

AppDelegate 实例声明如下：

 AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate];

改变这个，你很高兴。

Answer 4

1.确保您的 appDelegate 有一个UINavigationController名为navigationController.

2.代码的第 2 行： AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];

3.你的代码的最后一行： [appDelegate.navigat....
不是：
[AppDelegate.navigatio....